So the differential equation is de and its general solution is -rt/V Table 9.6 contains values of r and V for four of the Great Lakes.1 We use this data to calculate how long it would take for certain fractions of the pollution to be removed from Lake Erie ntity of pollutant) Table 9.6 Lakes Volume and outflow in Greai V (km3)r (km3/year) Superior Michigan Erie Ontario 12,200 4900 460 1600 65.2 158 175 209 t (ime) Figure 9.30: Pollutant in lake versus time